1. Technical Field
The present invention relates to an electronic apparatus and a method of controlling the electronic apparatus.
2. Background Art
In recent years, an IC card including a storage medium such as a flash memory as a storage device of a portable information equipment (e.g., a portable personal computer, a digital still camera, or a PDA), attracts attention. The portable information equipment handles a large amount of data such as music data or video data. Further, the IC card plays not only roles as a storage device for storing data and a bridge media for exchanging data between equipment but also a role as an apparatus for extending functions of equipment (See, for example, Non-Patent Document 1). Such an IC card including a plurality of functional units is referred to as a multifunctional IC card.
Referring to FIG. 15, a configuration of a multifunctional IC card according to a prior art disclosed in a publication will be described. FIG. 15 is a block diagram showing the configuration of the multifunctional IC card according to the prior art. The multifunctional IC card includes a plurality of functional units. A host apparatus and the respective functional units communicate with each other via a common interface part independently of one another (which means a fundamental communication form, and which does not exclude, for example, that the host apparatus transmits a common command addressed to a plurality of functional units).
Referring to FIG. 15, reference numeral 101 denotes the host apparatus, and reference numeral 1502 denotes the multifunctional IC card. The multifunctional IC card 1502 includes a controller 1511, a first functional unit 112, a second functional unit 113, and a third functional unit 114. The multifunctional IC card 1502 is connected to the host apparatus 101 via a bus 141. The bus 141 includes a command signal line 142, a data line 143, a power source line, and a ground line (the power line and the ground line are not shown in FIG. 15). The controller 1511 includes an interface part 121, which communicates with the host apparatus 101 via the bus 141.
According to the prior art, the host apparatus 101 is a computer. The first functional unit 112 is a memory module (constituted by a flash memory). The second functional unit 113 is a radio communication module. The third functional unit 114 is a camera module. The host apparatus 101 serves as a master, and the multifunctional IC card 1502 serves as a slave. The host apparatus 101 and the multifunctional IC card 1502 perform master-slave communication.
A method of activating the multifunctional IC card according to the prior art will be described.
When the host apparatus 101, onto which the multifunctional IC card 1502 is mounted, is powered on or the multifunctional IC card 1502 is inserted into the host apparatus 101, the host apparatus 101 supplies an electric power to the multifunctional IC card 1502 via the bus 141 (the power source line and the ground line). The host apparatus 101 transmits an activation command to the multifunctional IC card 1502. Activation of all of the functional units (including the controller and the respective functional units) of the multifunctional IC card 1502 is executed. Concretely, the controller 1511, the first functional unit 112, the second functional unit 113, and the third functional unit 114 are activated independently of one another. The activation of the respective functional units is sequentially completed, and when the activation of all of the functional units is completed, the respective functional units 112 to 114 turn operable.
Next, a method of operating the multifunctional card according to the prior art will be described.
The host apparatus 101 transmits an operation command (used as a block erasure command) to the first functional unit (the memory module) 112. The first functional unit (the memory module) 112 starts a block erasure processing based on the received command. The first functional unit (the memory module) 112 outputs a busy signal (Low level) to the host apparatus 101 via the interface part 121 and the data line 143 (the busy signal indicates that even if the host apparatus 101 outputs a next command, the first functional unit 112 cannot operate in response to the command). While the busy signal is outputted to the data line 143, the host apparatus 101 recognizes that the multifunctional IC card 1502 is operating. Therefore, the host apparatus 101 cannot transmit another command to the multifunctional IC card 1502.
When the first functional unit (the memory module) 112 completes the block erasure processing, the first functional unit (the memory module) 112 stops outputting the busy signal. Namely, the data line 143 turns from a Low-level output state to a High-level output state (a state in which an output of the interface part 121 has a predetermined impedance, and data can be transmitted, for example, from the host apparatus 101 to the interface part 121 via the data line 143). Then, the host apparatus 101 recognizes that the multifunctional IC card 1502 is ready (not busy). The host apparatus 101 can transmit another command to the multifunctional IC card 1502.
Next, the host apparatus 101 transmits an operation command (used as a received data output request command) to the second functional unit 113. The second functional unit (the radio communication module) 113 starts a processing for reading out and outputting received data stored in an internal memory based on the command from the host apparatus 101. While the second functional unit (the radio communication module) 113 is performing the processing for reading out and outputting the received data, the second functional unit (the radio communication module) 113 outputs a busy signal (Low level) to the host apparatus 101 via the interface part 121 and the data line 143.
A method of reactivating the frozen multifunctional IC card will be described below.
The first functional unit (the memory module) 112 starts a processing for writing data based on an operation command from the host apparatus 101. When the processing for writing data is not completed within a predetermined time, the host apparatus 101 judges that the first functional unit (the memory module) 112 is frozen. In addition, the host apparatus 101 transmits a reactivation command to all of the functional units of the multifunctional IC card 1502. Then, all of the functional units of the multifunctional ID card 1502 are reactivated. When activation of all the functional units is completed, the respective functional units 112 to 114 turn operable.
As stated above, in a system constituted by the host apparatus and the multifunctional IC card, the host apparatus and the respective functional units communicate with each other via the interface part independently of one another. Alternatively, another electronic apparatus is conceivable, in which one CPU performs all communications with a host apparatus via an interface part, and the CPU controls a part of or all of a plurality of functional units. The above-mentioned configuration of this multifunctional IC card has the following great advantageous effects. A common circuit (referred to as a controller in the specification) for integrating a plurality of functional units can be relatively small as compared with configurations of the other electronic apparatuses. It is unnecessary to change a basic configuration of the controller no matter what types of functional units are integrated. A period for developing and expanding an apparatus type can be shortened, and the various type of electronic apparatus can be expanded.
Non-Patent Document 1: “Matsushita Technical Journal, Volume 48, No. 2”, Ohmsha, Ltd., April 2002, pp. 20-23.
Recently, the multifunctional IC card has increasingly played a role as an equipment function expanding apparatus for adding an optional function to the host apparatus by attaching the multifunctional IC card to the host apparatus. One multifunctional IC card tends to incorporate more functions therein.
In the electronic apparatus (e.g., the multifunctional IC card) according to the prior art which includes a plurality of functional units and in which the host apparatus and the respective functional units communicate with each other via the common interface independently of one another, the host apparatus operates as follows. The host apparatus transmits an activation command or the other processing command to each functional unit. After the activation of all of the functional units is completed or a certain functional unit completes a processing, the host apparatus transmits a new processing command to each functional unit.
However, the respective functional units have an activation time different from each other. The electronic apparatus according to the prior art has such a problem that the host apparatus cannot transmit a command to the operable functional unit while the functional unit having a long activation time is active even after the activation of the functional unit having a short activation time is completed and the functional unit turns operable.
As functions of the electronic apparatus (e.g., the multifunctional IC card) diversify, there is such a problem that the time for the host apparatus to wait until all the functional units are completed with activation becomes longer.
Since the host apparatus judges whether the electronic apparatus is busy or ready as a whole and transmits a next command to the electronic apparatus, there is another problem that the host apparatus cannot transmit commands to different functional units in parallel.
Furthermore, since the host apparatus recognizes the electronic apparatus or multifunctional IC card as one IC card, there is the other problem that it is required to reactivate the entire IC card when one functional unit is frozen.
In the electronic apparatus according to the prior art, the host apparatus is incapable of confirming whether or not each functional unit is operable.
In the electronic apparatus according to the prior art, in order for the host apparatus to confirm whether or not each functional unit is operable, transmission of a command, for example, for inquiring the functional unit of its status from the host apparatus may be considered. However, when the functional unit is inoperable (inactive or incapable of responding to the host apparatus), the host apparatus cannot receive a response to the command. The host apparatus recognizes that the functional unit is inoperable, based on the fact that the host apparatus cannot receive the response to the command transmitted to the functional unit within a predetermined time (time out).
However, the predetermined time based on which the host apparatus judges that time is out, is far longer than the ordinary communication time. With a method according to the prior art, when one or more functional units are inoperable, it takes quite a long time for the host apparatus to confirm whether or not all the functional units are operable. In addition, the fact that no response is transmitted back to the host apparatus may possibly be resulted from the other cause than the function being inoperable. In the electronic apparatus according to the prior art, it is difficult for the host apparatus to accurately confirm whether or not each functional unit is operable.
In the electronic apparatus according to the prior art, all the functional units are activated. However, a user often does not use some functional units. The activation of all of the functional units including those which are not used causes unnecessary power consumption.